A stroke is a loss of blood to certain areas of the brain, causing the sudden death of brain cells. Strokes result in the loss of brain functions and can cause paralysis, memory loss, speech impairment, coma, or death. They are a medical emergency and are sometimes caused by hemorrhaging. Strokes, the third leading cause of death in the United States, are experienced by more than half a million people in the U.S. every year, and result in the death of over 150,000.
Beginning with an interruption of blood flow to the brain, a stroke progresses as oxygen is denied to the brain and waste products are unable to be removed. These functions, performed through normal blood flow, are sacrificed and usually end in the brief seconds- or minutes-long stroke. These stroke symptoms and results are more common in men, and affect people over the age of 65 most often. They require immediate medical treatment and can cause irreversible damage within minutes.
There are two main types of stroke: an ischemic stoke and a hemorrhagic stroke. In an ischemic stroke, blood traveling to the brain is decreased through any of several reasons. It can be the result of a blood clot or of blood loss from trauma or shock, and can start to alter the brain cells after mere seconds. The victim may not experience a stroke right away, but if the blood is denied for up to a few hours, the damage to the tissue can become permanent. The stroke will often occur as the brain cells cease to function and the victim experiences unconsciousness.
The other main type of stroke, a hemorrhagic stroke, occurs when blood accumulates anywhere inside of the skull. Bleeding can occur between the brain and the skull, inside of the brain, or outside of the brain, and is often accompanied by many types of headaches and previous head injuries. Different types of hemorrhagic strokes experience a wide range of death rates, from the deadly subarachnoid hemorrhage to the intracerebral hemorrhage, which has a death rate of around 44 percent.
There are many signs, symptoms, and risk factors for strokes. These include: changes in speech, numbness, reduction of senses, drooping of eyelids, altered breathing, altered heart rate, memory deficits, and loss of coordination. Symptoms like these combine to cause the death of 10 percent of people worldwide, and have done so for more than two millennia. Before 1599, a stroke was referred to as apoplexy, or as an apoplectic seizure, though doctors then did correctly suggest that a blockage in blood flow may have been the result.
